Active immunization with dendritic cells (DCs) is a new modality for therapy and vaccination in cancer. In our current studies of advanced melanoma, DCs loaded with either multiple MHC class I binding peptides or with killed allogeneic melanoma cells lead in some patients to durable clinical responses that are associated with tumor-specific immunity in blood. Patients who mount little or transient tumor-specific immune responses rapidly progress. We aim in this renewal to increase DC efficacy through clinical trials in patients, intertwined in a programmatic fashion and buttressed by lab studies. We aim to 1) improve DC processing of multiple antigens from dying tumor cells and their capacity to induce effector T cells, 2) use multiple DC subsets in tandem and characterize the distinct T cell differentiation they induce, 3) eliminate suppressor T cells by treatment with cyclophosphamide (CPA) prior to vaccination with DCs, 4) study myeloma to gain key information on the host response to DCs loaded with syngeneic tumor cells and in the tumor microenvironment. Melanoma studies will determine the activity of "composite DCs," i.e., Langerhans cells and other subsets. We will also assess a novel, more accessible, less expensive, GM-CSF and TNF induced, monocyte-derived composite DCs. Furthermore, we will test whether treatment with CPA prior to DC vaccinations will result in the improved efficacy. New York will test the efficacy of DCs loaded with allogeneic myeloma cells, and measure responses in both the blood and tumor-laden, bone marrow. The induced immune responses will be measured using our recently developed EPIMAX strategy. Ex vivo studies will determine the best adjunct therapy to DCs, i.e., CpG stimulation of plasmacytoid DCs, and toll like receptor ligands for mDCs. Mouse studies will improve DC efficacy at the levels of DC migration, T cell regulation and innate NKT cells, and will develop a new strategy of in vivo targeting of tumor antigens to DCs.